Dave, don't be blinded by the v.i., you (sorry, the fork oil producers) can influence it relatively easily with dopes (just look at shock oil with v.i. of even 400, they get really hot especially the ttx shocks with their small amount of oil). there are also things such as foaming behavior that strongly influence the operation of the dampers, cavitation etc. The viscosity is where you calibrate your dampers with the shims on and as such the 40 cSt is the most important for the "normal" users.
Thanks. Local tuner recommended Ohlins 7.5w, but the cost and extra deliverytime wasnt an option, so i used those online charts and cst values to find closests to Ohlins. Ended using Honda 5w.
Big thumbs up for a full vid of such an interesting subject. I use Belray 10w on my FJR 1300.. UK weather temps.. loaded panniers..96kilo rider. Progressive riding. Fork oil changes at 10k miles max for me.
thanks a lot dave . this one answered a lot of questions i had about the drop in viscosity of my MOTUL oils as things heat up. 20w sheds viscosity way sooner than 10w and i always wondered why. i ride a Royal enfield Himalayan on the dirt every weekend. pretty gnarly stuff and at good pace too.
Thanks, Dave! As I prep to replace my bushes and seals, its time for an oil change. Your videos always keep me pointed in the right direction. As California summer track days near, I plan to change from a 10w(spec) to a 15w on my stock 03 z1000. Hope to see you out at Thunderhill soon to pick your brain about this.
Thank you Dave!! I have no -adjustable forks and live in Las Vegas. Will be swapping out the factory oil to Maxima 20W for my weekend spirited rides and track days. Not a commuter bike.
Centistokes and kinematic viscosity are the same. Centistokes is just the unit to measure kinematic viscosity like metres are used to measure length. en.m.wikipedia.org/wiki/Viscosity
Having previously made the mistake of assuming a higher V.I. Is always better and finding out that as the viscosity index goes up the lubricity goes down, as a general rule. Therefore high index oil are best for cartridge dampers and avoided for open bath lubrication. I personally damaged a great fork making this mistake
Brilliant explanation to consolidate what I sort of knew. Multistrada 1200, regularly 35+ Celsius climate, 110kg rider, ridden pretty hard and running out of fork valving adjustment so I think it's time to move to a heavier more stable oil than the 7.5w Shell.
Thermal coefficient of expansion is involved too. Oil volume expands with heat, contracts with cold. Not so much a factor for forks that already have an air gap or motor oil in a crankcase but expansion affects smaller volumes much more. This is why reservoirs for brake master cylinders or steering stabilizers have to have an air gap to work right.
(At least fork oils that I’m familiar) are tested according to ASTM D445 for viscosity both 40C and 100C temperatures. Since this is single grade W( winter) rated oil, SAE W viscosity rating is based on -30C(?). For e.g 10W oil can have 32 or 54 mm2 at 40C (these are real values, not just theoretical example). I also recommended always checking fork oil datasheets from manufacturer’s website (typically acc. to standard it is required to have and show both; technical datasheet and safety datasheet), since it list both 40C and 100C values. Both values matter, but 40C value is more important. No don’t work directly at petro-chemical industry and I don’t know ASTM 445 or SAE standards well (but I know ton of other standards), so hopefully someone expert on these standards could correct me if I’m wrong. Great Video Dave.
The St (Stoke) and by extension cSt (centiStoke) are the non-SI units of kinematic viscosity. The SI unit is m^2/s. But fundamentally they're measuring the same thing and the conversion is very simple - 1 cSt = 1 mm^2/s or 1e-6 m^2/s. Kinematic viscosity itself is a derivative quantity. It is the ratio of dynamic viscosity and density (nu = mu/rho). In hydraulic dampers, where the important property of a fluid is its resistance to flow through an orifice, kinematic viscosity is the right quantity to work with as it neatly abstracts away the interaction between density and viscosity in this type of flow. Doesn't hurt that fork oil is more or less incompressible either.
Fantastic knowledge you have , incompressible is a new word for me.👍can I ask, are a motorbikes front forks basically a hydraulic ram with a internal spring? If so , as someone else previous mentioned can I use hydraulic fluid in the bikes front forks?
@@mfitzgerald130 Part of the job - I work in thermo/fluid dynamics. It's super interesting stuff, but you've got to have the patience to go to the depth necessary, otherwise none of it makes sense. Anyway, back to forks... They're not really hydraulic rams in the excavator sense. They're dampers. They dampen oscillations (i.e. take the bounce out of the system) by forcing oil through a small orifice (or a few, or an annular gap... another big word to learn 😉) any time there is motion. The resistance of the fluid pushing through is proportional to the rate at which it's being forced through (closer to a square relationship, actually), so it works really well at taking away oscillatory motion. It does however rely on the properties of that oil, specifically on its kinematic viscosity. Too much will overdamp the system and too little will leave it bouncy. The latter, famously, being a problem on MT-07s from the factory. To that end, it's usually best to follow manufacturer recommendations here, as they've done the R&D to determine the correct grade and more importantly, the correct type of oil to use there. Or at least they should have (see MT-07). Hydraulic, automatic transmission and fork oils are generally related, insofar as they're all hydraulic working fluids, but I suspect they're different enough that using regular hydraulic oil probably won't yield the best results (plus that sh!t will kill you if it enters your blood stream, NASTY!!!). Inside, forks are made of a few metals, some plastics, and rubber, which is broadly similar to automatic transmissions and hydraulic systems, so it's _possible_ that using a different type of oil (like ATF) wouldn't damage anything, but I wouldn't risk it. Too much can go wrong even if your forks are just out of whack rather than outright damaged. The "spring" part is actually two springs - the coil spring you pull out when you service the thing, and an air spring made of the air gap above the oil. As you compress the forks and thus pump oil into that void, its air volume decreases (because it was filled by oil), so the air must compress (usually they're sealed). Then when the fork extends the air can expand again. Effectively a gas spring. That's why oil level in your forks is important, and why you can change their spring properties by adding and removing oil.
SV 650 Gen 1, classic damping fork rod Spirited road driving above 24 C, pilot 85 to 90 Kg. Stock springs: Motul 15W, a bit too thin for rebound. WP spring: Motul 20W good rebound (need a bit of tuning for the oil level/air gap to prevent harshness on compression).
2009 Victory Vision. Very heavy bike. Swapped out fork oil for Redline 10wt. Quantity to spec. Very stable behavior and just fine. So far so good, FWIW.
I can't read the owner's manual because the forks on my 1967 Kawasaki are actually from an Unknown 80cc MX bike, probably early 80s. The forks have no brand markings and were pulled out of a heap of "old cycle parts" in the 90s. So we have to fall back on first principles with these. They work pretty well on ATF+4, (which I'm told is roughly equivalent to like a 7w fork oil?) but sure do leak a lot with it. Lol
Thought I was with ya but you said two things that appeared to conflict, and I got confused. First, faster pace riders (weekend twisty road enthusiast vs commuter) might need a lower weight oil, and second that a rider on an MT07 who rides hard on the weekends may prefer the 20w over the 15. I have an MT07 as my first bike, and I've been progressing quickly in my riding, and I've begun thinking about simple/cost effective modifications I can make to suit me better and learn more about motorcycling in general. The suspension is a gripe I hear of continually but, being that it's all I've known, I don't know WHAT I don't know, and I've been wanting to try changing to a different fork oil to see what it does to the handling and whether it's an improvement for me or not. I like to ride briskly (Top of third gear into fourth ~60-80mph in every straight possible between the curves) and brake moderately hard, not at track pace of course - but about as hard as is feasibly safe on public back roads. I weigh 190 pounds and live in an area with a riding season temperature range between about 40 and 95 degrees Fahrenheit. I'm not sure what the best choice could be.
Thank you for your comment. For cartridge forks, sometimes thinner oil is needed for better flow and handling as there are adjusters to use. For damping rod forks thicker oil is needed to create more controlled rebound. With your MT07, 15 or 20w oil will make an enormous difference and start your journey of changes that create positives vs adapting to suspension.
The base oil (base oil is the oil from the refinery without any additives) has a certain VI depending on type of base oil. Mineral base oil has usually a max. VI of 105. And a PAO synthetic (most common synthetic in automotive use) has a VI aprox. 130-160. This VI will not decrease due to shearing. So mineral oils has to be more additivated with VI improver to have a more consistent behavior in chocks. But VI will decrease due to searing over time. Synthetic oil needs non or less VI improver and thus better keep it's viscosity over time. PAO also have a better flow behavior.
Ive been thinking about fork oil recently as I need to change it on 4 bikes. I reckon hydraulic fluid would be more than suitable and it is tightly regulated. In its normal application it has to withstand very severe operating conditions, so I doubt it would struggle with bike forks. It also comes in mineral and synthetic types.
Peter verdone has a chart that's it's weight in gold , and if you know how to chart it onto sheets/excel, it's like sniping a toothpick from a mile away , it's that powerful of a tool.
Dave you should watch a Project Farm oil test with his flow check of new vs used oils (like a pinewood derby track). Would be interesting to do with various folk oils at hot and cold temps.
Interesting video, having just cleaned/serviced the forks on my Aprilia Pegaso Strada (commuter) and changed to 15W. On the West Coast of Scotland, which was dry (Woo Hoo) the difference was very noticeable in both compression and rebound damping and I could ride a lot harder/faster with improved feedback. Heading back to Edinburgh, due to rain and average speed camera's the change wasn't so noticeable. I'll keep notes and try 20W the next time.
I've got a 22 CRF 450 and when I got it the forks were solid to move so I got the lightest spring rate from honda and rebuild them to find it's already got the lightest spring in it! I used the correct oil and levels the manufacturer states but it's still a harsh ride I've checked the fork alignment many times and my adjustments are opened right up but it's still crap but I'm about to send the top tubes for a regrind and anodising so I'm trying 5w when I rebuild them this time
I would suggest that you take the chrome and outer tubes and have them put into a lathe and tested for run out to see if the tubes are binding. I would check the bushing as well and look at the chrome tubes for scoring from the bushings.
useful video: Question: I know what temperature rear shock oils can and do reach but, not seen figures for 'in use' front fork oil....I'm taking an educated guess in that it's over ambient so that negates worries over regional temperatures.....wouldn't it? ....damper rod front forks typically have a longer stroke than a rear end but, a higher oil capacity and out in the air stream. It can't be that high as I've never seen cooling aids for front forks...? Next time I return from a ride I'll take some temperature reading using my infra red gun. Luckily I have crude damper rod forks so it's all a finger in the air compromise. It's a shame fork oil isn't manufactured to strict standards like ATF's....Dexron 3, spot on the spec' as Suzuki/Showa SS8 which is handy if you ride a Wee Strom DL650.....not recommended for the DL1000 which uses cartridges and needs fairy spit.
If you run forks on a dyno, oil temp can reach 100C hence flow rates being posted at 40 & 100C by manufacturers. MX bikes generally run much higher temps due to velocity/movement.
The reason for using 'fairy spit' ultra low viscosity fluids is they are more temperature stable than higher viscosities. If there weren't other effects in play, we'd be using water or alcohol for viscosity stability across a temperature range. Forks have more oil, and most commonly the load divided between 2 forks, and more surface area to providing cooling, so they get less hot than shocks. Differences in high flow vs high pressure style valves make a big difference in heat and wear... if being aggressively ridden. Daily commuting with an easy relaxed pace may not even warm forks above cold to the touch. Extreme MX can have a shock so hot that flash point is being considered...
Hi Dave, you helped me set up my f&r suspension on my 2020 1050XT Suzuki V-Strom via email about a year ago when i got it new. It is really dialed and I love it thanks to your excellent advice. I will be doing my winter service now, including the dump & run on the fork oil. I ride a very spirited pace in the mountains, weigh 164 lbs. w/o gear and carry probably 25 lbs. gear. Based on the CST charts, I am thinking Maxima 7.5W is right. Can I set my oil level/air gap without disassembling and removing springs? My riding temps will vary from 90f-40f. Many thanks as always!!!
I'm old enough to remember when Japanese manufactuers used fish oil in damer rod forks......and you think well used modern fork oil stinks, well you haven't lived.
There are many choicees but please Google an oil viscosity chart first to get your base VI and CsT numbers, then compare with the manufacturer's data if you are considering ATF etc.
I have a 07 CBR 600RR manual says 10W here in north east.. i commute and weekend drive with friends. I dont wheelies or track . Whats should i used better. Im about to do it this weekend... Brand and W. Thank you
Oh my Gosh! I can't believe how little I knew about fork oil! Thank you so much for showing me that there is a real measure of viscosity. I just rebuilt the forks on my 2008 GL1800 and added Progressive springs. I'm still trying to decide what fork oil to use. I suspect that I want something a bit heavier than the 10w OE oil made by Showa. If it wasn't such a pain to drain and swap fluid, I would just go in with Maxima Racing 15w and try it out. I have even though about mixing 15w with 10w to get 12.5w. Would you be kind enough to give me some guidance?
Thank you for your comment and kind words. May I suggest going straight to 15w for your generation of Goldwing. Use the stock volume in the service manual and compare to what you extract prior to deciding how much to put back in. You should notice a small loss post draining compared to the manual amount. Please take that into account.
Hi Dave. What would recomend for oem k7 gsxr forks? All weather riding, mostly short commutes but I like to have fun out in the lanes too. Your vids are great tools so thanks for your help.
All weathers would generally suggest cooler climate overall with the exception of hot Summer days. My go to would be Maxima 7.5w and stock volume of oil.
@@catalystreactionsbw Cheers Dave. I don't think the oil has been changed once and I have the preload fully soft, despite being about 225-230 in full gear. If I stiffen preload it starts to feel like the front is on the head of a pin and very unstable. Could this be due to the oil being so high in viscosity, being so old? I was planning on changing the forks, with stiffer springs but I just don't have the funds right now.
I was at the track recently and under heavy braking only the front end would judder up and down in small movements. I'm unsure if i am expirenceign cavitation or maybe my discs are so slightly warped. The front wheel doesn't turn freely by hand but i put this down to filthy calipers because my bike is also my daily and the uk roads get rained on a lot so all that shit gets all over my bike every day.
Check the brake pads for angulated wear, then grab the forks by the bottom and see how much free play you have. Could be brakes, bushings or steering head, or a combination.
The oem Yamaha 01 fork oil for the mt10 seems to have to same numbers as the motul and maxima 5w , should I stick with that weight when changing do you think , spirited riding two's up on weekends , or shall I go slightly higher in numbers there for needing less preload and more range , I didn't think it would be this hard choosing a fork oil 😁
@@catalystreactionsbwmuch appreciated I'll stick to something very close to those viscosity numbers then , just another quick question as I don't fully understsnd the mt10 service manual fork oil level , does it mean 114mm air gap from top of the oil to the top of the fork tube with the spring out if I'm doing seals and if just changing the oil can i just do what you have done on the dump and run when you measure the amount poured out and match that back in again , thanks again for the helpful videos
@@bccapone837 You can do the dump and run but draining will take a while so be patient. Same goes with fresh oil going in. Takes time. Noted on the UK and yes, lighter oil makes sense.
Installed Hyperpro springs, with included Hyperpro oil 10W. Standard damping rod forks, freshly rebuilt. Too harsh on sharp bumps, rebound too slow when fully out, almost 20 mm of stiction. Twice tried loosening axle, lower tripple clamps, steering stem nut, bounce the forks to allign everything and torque everything down. Nothing. Decided to dump the Hyperpro oil and put in Motul 10W. Faster rebound, not too fast, down to 10 mm of stiction, and smoother over sharp bumps. Why would they not standardise fork oils? And why so much friction with Hyperpro 10W?
@@catalystreactionsbw Thank you for the response, and everything you do to share your knowledge. It means a lot to us DIYers on a low budget. It was greased when installed, I even tried "forcing" some grease by greasing the stanchion and rapidly compressing it, after it didn't help I tried doing the same with silicone spray. Is there any chance that Hyperpro oil is just subpar? I doubt a company would deliberately sabotage themselves with bad oil.
@@KarloZg9000 as usual you covered it perfectly . Ideally one picks a 0 or 2.5 weight oil for the least temp effect. And valve and piston design for that bike using the least weight. I found your reasoning for no mechanical changes to be excellent. We use belray. Because we are to cheap to buy 55 gallon drum of koni 0 weight which is the only way they sell it. And the only source I know of.
Leadership by example?!!! Yeah, we were taught the same pay it forward attitude. Will do, chief! Hope you and all do yours have a nice 21 summer season. 😉
Great info as always. I have a Moto Guzzi Audace cruiser, 660lb bike + 200lb rider. I'm just about to get my mechanic to upgrade the OEM front and rear suspension to Matris suspension. What weight fork oil do cruisers usually run? I'm looking for sportier more responsive feedback riding at 15°C to 30°C temps.
Thank you. Are you referring to air in the oil? Higher viscosity oil by default moves slower so the opportunity for air to be introduced to the oil is limited. Track days are generally easier on suspension as race tracks for the most part are significantly smoother than roads you ride on.
Is it wrong to use 10w40 engine oil in Chinese forks? Thinking about application and market. Most of these bikes are for far east sale so the small numbers sold here in the west is mhhh to the manufacturer. Accessablity of exotic oil for forks in these regions and the means to purchase, meaning we in the west are blessed to afford such things. 10w40 engine oil in Chinese 125 forks right or wrong?
Dave, Great video, thanks! I have 3 Honda ST1100's (I have issues, LOL) I have Maxima 10W in all 3 bikes.The forks on 2 of them work as they should here in So Cal. My oldest, a 1995 ST's forks feel a little mushy compared to the others yet is very plush on the highway. According to Honda part #s all internals are the same. Cartridge on the right and just a spring on the left. I can't decide 15W or 20W, what would you recommend? Any help would be greatly appreciated.
A lot to take into consideration, fun to tinker with however. Thank you so much for this work! Do you have experience with the Tracer 900? What oil would you choose for spirited riding for a 75 KG's rider that typically ride between 10-25 degrees celcius?
I have one in NZ and did all the work on it there in a relatively cold climate. 10w for rebound and 15w for compression. All that work is posted on my website at www.davemosstuning.com and search Tracer GT and "The Long Haul" articles for OEM settings, geometry etc.
Is this numbers for the motul synthetic factory line fork oil? Or the cheaper mineral based fork oils.? Is maxima fork oil synthetic? The 2011 gsxr 1000 has the SS-05 for oil stock which is showa 5W not sure if it's synthetic ...would the motul factory line synthetic 5w be a better replacement oil at fork oil service time or should I stick with the suzuki showa SS-05...?
Hi Dave, I live in Las Vegas. I have a 2022 Indian Scout Bobber. I will be installing a Legends AXEO fork suspension but I would like your recommendation of what Maxima fork oil weight to use?
Still confused.... lol Bought a 2021 mt07. 215lb rider. No track riding. Just a weekend rider (Toronto, Canada) Not sure if bike is delivered to the dealer with fork oil, but if it isn't, should I ask the dealer to put a specific W fluid in? Picking up bike end of month/early July. Love the videos DMT!
Not seeing much examples for a 600cc/1000cc. I have a 2012 kawi zx6r. Definitely ride hard (highways,backroads, mountain, cornering,commuting). As I’m seeing, would a… hmmm… 20w be suitable ? Is this wrong ? I am thinking it terms of what can handle an aggressive riding style. Normal weather/riding conditions range from 50- 95 degree weather and I’m around 190-195lbs athletically built.
Have you set the suspension to your weight and ability and checked fork and shock travel used? That will show if the suspension is too soft or hard and give you the accurate data to guide you to the right changes.
@@catalystreactionsbw I have .. i am actually 170 lb (lost weight) lol . I actually realized the spring rate for the 2012 zx6r are pretty stiff stock (.95kg). All my preload is all the way out and can only achieve a sag of 27mm front. I’m using half of the travel at normal braking and off hard braking I just reach what it seems to be the right buffer before bottoming out. Just recently did fork oil and my tech used 5w. Looking for a spring rate of .90kg so I may achieve a sag range from 30-40mm up front. Recommend ?
@@junerobinson1220 90 would be a good idea BUT the math must be done in regards to spring length and installed preload as the internal spacer will need to be made shorter. You lack of static sag is a known problem that needs to be resolved.
@@catalystreactionsbw will note that during my inquiries of the right spring 👌. And right, my concern for the lack of static sag is there. Is it okay for the front and rear sag to be different numbers? For now, as my front preload is all out maxing at 27 mm… Can I decrease preload in the rear and get maybe 29-31 mm to get some static sag ? From your videos , I understand a slightly lower front and raised rear helps with turn in?… (although I’m street) My bike is slightly hard to turn in initially but falls into the corner after and follows ( dunlop Q3+) Tire pressure 34 front 36 rear.
@@junerobinson1220 Front can be profoundly different to the rear based on fork and shock travel optimized to your roads and pace. Get 10-12mm static in the rear shock and see how much shock travel is used: th-cam.com/video/KeZT1LCY8CU/w-d-xo.html
I have a 2014 Triumph Tiger ABS, not the XC or any more off-road version. I just purchased the bike a few months ago with about 7800 miles on it. The local service guy says the bike is designed for lighter riders, I'm about 225-230 pounds. He said I should think about changing to higher W oil and maybe different springs. According to Haynes manual the fork is: Showa 43 mm upside-down cartridge forks, non-adjustable. Any suggestions to improve my ride for 85 road - 15 trail, pretty non-aggressive rider.
I would suggest 15w oil and 50ml more than the manual suggests for volume. Thus will be a dump and run project for you! th-cam.com/video/UoIQNcxqaSA/w-d-xo.html
Motul 10W too hard action & less travel. Motul 7.5W too soft & over travel. Mix both 50/50 equals Motul 8.75W. Ureka I've done it. Good action & near max travel. May change to Maxima. 7
Hi Dave, if i recall you have a bandit 1250 as well. Would you recommend the RaceTech Gold Valves? I am a 150lb rider that uses the bike across a wide array of roads/styles. I currently have 1.1kg/mm fork springs and Redline 10wt oil. I have tried 1.0kg/mm springs but was unable to achieve proper sag without too much preload and a rough ride. The oil previously was too thick for the heavier springs and produced a harsh ride. Redline 10wt improved ride quality and I plan to try Redline 5wt then mix to a 7.5wt if needed. Handling seems great but I am picky and would like a bit more of a plush ride without costing performance.
Great R&D on oil. A tip of the hat to you. The issue with the forks is the compression pistons in that the valving is very soft hence going to strong springs with lighter oil as the optimal solution. Changing to RT Gold valves will help for sure as they come with a lot more compression valving and use 5w oil for more plush suspension action.
@@catalystreactionsbw I appreciate the feedback! Will you be in the Northern California Bay area this riding season? I plan to hit the tracks after dialing in the suspension on the streets.
Hey, can someone confirm this theory of mixing viscosity for once and for all? I grew up messing with mountain bike suspension (still do) and I still mess with vintage motorcycle suspension as well as high end stuff (rsv4), so I don't always have the option of adjustable valving, or I do an oil change thinking 10w would be enough only to find its still too thin. From what I remember, to get 12.5w, is it true that you need 3/4 of the volume to be 15w and 1/4 of the volume to be 10w? Or the other way around?
*It's a very close approximation to use a simple proportion equation.* And you should use cst or kinematic viscosity, not 'wt.' Pick the temp range you want (eg cst @ 40C) In decimal: [desired cst] = Pax[cstA] + (1-Pa)x[cstB] re-arranging that to solve for the P (the proportion): *Pa= (desiredcst - cstB)/(cstA - cstB)* multiply that by 100 if you want a percentage The proportion of B is just the remainder Pb= 1 - Pa, or in percents Pb% = 100% - Pa% Eg (should be using cst instead of 'wt'): Pa=(12.5-15)/(10-15) Pa=0.5 x100, if you prefer = 50% And since A is 50% B = 100%-50% so coincidentally B= 50% as well. Which makes sense, because the chosen 12.5cst is halfway between 10 and 15, so no surprise you need a half-and-half proportion to reach that. If you really care, you will do this and see what the combined effect is at other temperatures too, so you see what your new oil mix line will look like. *Unless you are an engineer designing something critically sensitive, you should never need to go deeper than simple proportions within the same oil series for determining your mixtures.* Note: *if your desiredcst is outside the range capable with your mixes, instead of a decimal number, you will get a number greater than one or a negative number, which are non-sensical as a proportion of a whole.* e.g. 45cst: In reality, what does it mean to add -6 of A? And B being added at 7x the total mix volume? Are we distilling -600%A out of 700% B to end up with 100%? Non-sense for our purposes. Tiny note, maybe ignore this because you don't need to know it: the mix may not wear evenly with time, so expect a manufacturer created oil to have the most long term stability, but this effect is still likely to be small/insignificant if you've chosen use-stable oils.
Those oingo boingos need lubricant to operate smoothly and the oil serves as resistance through the valves to slow down shock action. With out oil you are riding an expensive pogo stick. Too much and too thick it’s a lumber wagon with solid axles. Done correctly it’s smooth sailing with superb control.
@@kariholma3850 They should have different additives as they both have different purposes. That being said, I am sure some fork oils are just branded hydraulic oils. I would like to hear details from people i the know. Personally I use hydraulic oil in my bike's forks. They work well for me. I am not racing though. The advantages of hydraulic oils are that the data is easy to find and there is a lot less hype and marketing involved so they are cheap enough to be able to optimise your fork's behaviour through trial and error, reaching your preferred viscosity even if that means mixing two standard viscosities:-)
Seriously, the manufacturers & fork oil companies do not provide guidelines as to which oil to use bc it's all relative, like Dave said, to how you're gonna use the bike. I had prior ordered Pro Honda/Showa SS-8 assuming it is most reliable for my CBR600RR.
Nice Vid as always! Thanks! I learn a lot from it! but what Fork oil do you think should I put to my Duke 200 Stock Forks? I use the bike for daily and sundays at twisties, aggresive riding also . I live in the Philippines which is have a mixed weather and temperature around 20C - 35C.
@@kaiserdgreat I have not seen one in person. Depends on the odometer reading. If the forks are the same as the 390 base model, 15w oil works if you are over 70kgs, 10w if less than that. Maxima is great oil.
This is so damn helpful! The details and how you explained it helped me understand whcih oil grade to use. I have studied this in college, over 2 decades ago and totally forgot it hahaha Was trying to figure out what WT to use on my MTB fork and now I know. Thank you so much!
Thank you for sharing Dave, in my service book mention 20W for fork oil. I live in mix climate.. Lowest is 15 degree celcius and maximum is around 38 to 39 degree celcius.Is it still ok I use 20w? My small bike is Kawasaki Kaze / modenas kriss
I'm a layperson, but in layman's terms I've heard that independent of cSt, a higher Viscosity Index oil potentially has greater stiction and isn't as slippery. A super high VI oil may be needed for a shock that can get quite hot, but for a fork, too high of a VI may be detrimental. Is that a linear relationship? Is a higher VI oil always 'stickier' than a lower VI oil, or is it not that simple? Can anyone elaborate?
That is correct and well stated. There is no linear relationship de to various engineering solutions created in each fork from different manufacturers. In the case of Ninja 400 forks with no adjustments, VI ensures that rebound is correct for a given period of time, then it must be replaced when rebound is too fast from broken down oil. With cartridges, most are engineered today for 2.5 or 5w, but internal engineering with valving allows for some flexibility with VI based on regional temps eg Death Valley to Vancouver BC. Hope this helps.
@@catalystreactionsbw Thanks for taking the time to reply. When I got started down this rabbit hole of understanding suspension oils better, I presumed you wanted the highest VI you could get your hands on regardless of application. I guess I know better now. This is all interesting stuff. In a 2019 WR250F (cartridge forks) I'm about to switch from 15.6 cSt OEM fork oil to 18.9. I'm a 240 lb rider. Do you think I'll feel a difference beyond what I can adjust with damping clicks? OK to go thicker?
Hi whant to no can i put a stronger rear shock on my xr honda ct 190 this one is to soft and can i put on my front fork tronger oil 20w my weight is 85 kg on the bike i use my bike on the farm
what u recomend for speed four triumph??.. i ride it in hotter climate, from 17 Celsius to 35 Celsius... i dont comute with it often.. i ride it more on weekends on highway and mountain roads..tnx
@@catalystreactionsbw we have motul and motorex were i live.. i think that every motul product is overprized in my country...i use motorex oil in my bikes, so ill try the fork oil than... tnx a lot man.. ur advise meens a lot.. ur the best
@@OppoAs-zh1bd not much difference from the stock actually, though now I'm pushing a bit harder and have adjusted the suspension settings properly to my weight.
If i understand you correctly, you are talking about air pressure from 90psi to 160psi as an example with a Supermoto air fork. In dialing the air pressure, I always start at the minimum value to see how much movement and how fast the movement is on initial braking and bump compliance. I will also use fork travel used as an additional data point. I will then change to maximum pressure to check harshness, then at 50%. Once you understand the pressure zone that works, then you can explore smaller changes.
Hello Dave. I have a Suzuki VZ800 year 1998. I live in Portugal (minimum temperature 12ºC and maximum temperatures sometimes reach 40ºC). What is the best fork oil to use? 15w ? Thanks
Hi Ricardo. Thank you for your question. 15 or 290w based on your weight and duration of rides (heavier weight if you ride for 1-3 hours at a time at speed vs short urban rides).
What about 30w in something like a Ninja 650, mostly commute, in average 90F temps? Your missing any 30w numbers, but I guess I should learn to work my own butt ( look it up). I do have Maxima 30w in my 1986 Yamaha SRX600, plus Progressive fork springs and 10mm longer spacer.
What are your thoughts on mineral fork oil... Does it do any damage on a heavy cruiser... I ordered 20w online and didn't realise until I put it in my forks that it's a mineral oil
Mineral oil will not damage your fork internals. There are rubber o-rings and teflon bands inside the cartridge if you have that system. If you have a damper rod, that is simply metal. All good!
The metal of the fork does not, but the oil temperature does especially on rough roads due to the velocity of movement that it constantly goes through. Simple friction and pressure.
@@catalystreactionsbw so does the oil in a engine going through pumps, squeezing through bearings, all wrapped up in ferings and it barely gets that hot unless there's a lot of traffic and idleing.
@@nick4506 Great question. The engine has the added heat of combustion along with friction and flow via the pump. Fork and shock dyno's can record oil temps and that is where the data is drawn from.
@@catalystreactionsbw huh interesting. how effective can that static pogo test be, looking for bounces one, if all oil becomes thinner then cool 5w when riding? difference between the lightest and heaviest at 100c is less than the difference between cool maxima and motul 15w.
Hi Dave, so i am an 75 kg / 165 lbs rider, riding relatively hard in summer weekends, road bike never been on track, temps 25 to 35 *Celsius, stock suspension on my GSXR 600 k7 (2007) what fork oil do You reccomend?
@@catalystreactionsbw sorry, You mean motul 7.5w with orange-ish label? "road and off road, light-medium, factory line" thats the only one i can find on google...
@@catalystreactionsbw hey Dave, i got another problem, i cant get maxima oil in Croatia.... can you please please please send me a motul oil link..... i am not sure what motul oil should i use because there is many motul forkoil "factory line, expert, etc.." thank you so much!...
Dave, don't be blinded by the v.i., you (sorry, the fork oil producers) can influence it relatively easily with dopes (just look at shock oil with v.i. of even 400, they get really hot especially the ttx shocks with their small amount of oil). there are also things such as foaming behavior that strongly influence the operation of the dampers, cavitation etc. The viscosity is where you calibrate your dampers with the shims on and as such the 40 cSt is the most important for the "normal" users.
Excellent contribution, thank you.
Thanks. Local tuner recommended Ohlins 7.5w, but the cost and extra deliverytime wasnt an option, so i used those online charts and cst values to find closests to Ohlins. Ended using Honda 5w.
Is there a “go-to” online chart?
Thands Dave. Lots of useful information there. Will try that out with next fork seal change.
Big thumbs up for a full vid of such an interesting subject. I use Belray 10w on my FJR 1300.. UK weather temps.. loaded panniers..96kilo rider. Progressive riding. Fork oil changes at 10k miles max for me.
thanks a lot dave . this one answered a lot of questions i had about the drop in viscosity of my MOTUL oils as things heat up. 20w sheds viscosity way sooner than 10w and i always wondered why. i ride a Royal enfield Himalayan on the dirt every weekend. pretty gnarly stuff and at good pace too.
I feel smarter every time I watch your videos Dave. Thank you
Andrew Wiltse?? The famous Jiu-Jitsu blackbelt competitor??
Thanks, Dave! As I prep to replace my bushes and seals, its time for an oil change. Your videos always keep me pointed in the right direction. As California summer track days near, I plan to change from a 10w(spec) to a 15w on my stock 03 z1000. Hope to see you out at Thunderhill soon to pick your brain about this.
That will b a great choice, stick with Maxima or Motul
Thank you, I'm glad I became a member! Really great info. I thought switching brands between W numbers was really similar! Doh!
Thank you Dave!! I have no -adjustable forks and live in Las Vegas.
Will be swapping out the factory oil to Maxima 20W for my weekend spirited rides and track days. Not a commuter bike.
Thank you for wanting to learn, understand what is needed and get the job done!
Centistokes and kinematic viscosity are the same. Centistokes is just the unit to measure kinematic viscosity like metres are used to measure length.
en.m.wikipedia.org/wiki/Viscosity
Having previously made the mistake of assuming a higher V.I. Is always better and finding out that as the viscosity index goes up the lubricity goes down, as a general rule. Therefore high index oil are best for cartridge dampers and avoided for open bath lubrication. I personally damaged a great fork making this mistake
Thanks for sharing your knowledge and experience Angus!
This video was awesome, highly detailed but simplified enough for general understanding!!
Brilliant explanation to consolidate what I sort of knew. Multistrada 1200, regularly 35+ Celsius climate, 110kg rider, ridden pretty hard and running out of fork valving adjustment so I think it's time to move to a heavier more stable oil than the 7.5w Shell.
tq so much sir,this realy helps me which is only 42kg(abnormal) of weight to have fun riding
Thermal coefficient of expansion is involved too. Oil volume expands with heat, contracts with cold. Not so much a factor for forks that already have an air gap or motor oil in a crankcase but expansion affects smaller volumes much more. This is why reservoirs for brake master cylinders or steering stabilizers have to have an air gap to work right.
Dave, you asked me at Thunderhill if I had 20W in my forks. Now I understand why.
(At least fork oils that I’m familiar) are tested according to ASTM D445 for viscosity both 40C and 100C temperatures.
Since this is single grade W( winter) rated oil, SAE W viscosity rating is based on -30C(?).
For e.g 10W oil can have 32 or 54 mm2 at 40C (these are real values, not just theoretical example).
I also recommended always checking fork oil datasheets from manufacturer’s website (typically acc. to standard it is required to have and show both; technical datasheet and safety datasheet), since it list both 40C and 100C values. Both values matter, but 40C value is more important.
No don’t work directly at petro-chemical industry and I don’t know ASTM 445 or SAE standards well (but I know ton of other standards), so hopefully someone expert on these standards could correct me if I’m wrong.
Great Video Dave.
The St (Stoke) and by extension cSt (centiStoke) are the non-SI units of kinematic viscosity. The SI unit is m^2/s. But fundamentally they're measuring the same thing and the conversion is very simple - 1 cSt = 1 mm^2/s or 1e-6 m^2/s.
Kinematic viscosity itself is a derivative quantity. It is the ratio of dynamic viscosity and density (nu = mu/rho). In hydraulic dampers, where the important property of a fluid is its resistance to flow through an orifice, kinematic viscosity is the right quantity to work with as it neatly abstracts away the interaction between density and viscosity in this type of flow. Doesn't hurt that fork oil is more or less incompressible either.
Fantastic knowledge you have , incompressible is a new word for me.👍can I ask, are a motorbikes front forks basically a hydraulic ram with a internal spring? If so , as someone else previous mentioned can I use hydraulic fluid in the bikes front forks?
@@mfitzgerald130 Part of the job - I work in thermo/fluid dynamics. It's super interesting stuff, but you've got to have the patience to go to the depth necessary, otherwise none of it makes sense.
Anyway, back to forks... They're not really hydraulic rams in the excavator sense. They're dampers. They dampen oscillations (i.e. take the bounce out of the system) by forcing oil through a small orifice (or a few, or an annular gap... another big word to learn 😉) any time there is motion. The resistance of the fluid pushing through is proportional to the rate at which it's being forced through (closer to a square relationship, actually), so it works really well at taking away oscillatory motion. It does however rely on the properties of that oil, specifically on its kinematic viscosity. Too much will overdamp the system and too little will leave it bouncy. The latter, famously, being a problem on MT-07s from the factory.
To that end, it's usually best to follow manufacturer recommendations here, as they've done the R&D to determine the correct grade and more importantly, the correct type of oil to use there. Or at least they should have (see MT-07).
Hydraulic, automatic transmission and fork oils are generally related, insofar as they're all hydraulic working fluids, but I suspect they're different enough that using regular hydraulic oil probably won't yield the best results (plus that sh!t will kill you if it enters your blood stream, NASTY!!!). Inside, forks are made of a few metals, some plastics, and rubber, which is broadly similar to automatic transmissions and hydraulic systems, so it's _possible_ that using a different type of oil (like ATF) wouldn't damage anything, but I wouldn't risk it. Too much can go wrong even if your forks are just out of whack rather than outright damaged.
The "spring" part is actually two springs - the coil spring you pull out when you service the thing, and an air spring made of the air gap above the oil. As you compress the forks and thus pump oil into that void, its air volume decreases (because it was filled by oil), so the air must compress (usually they're sealed). Then when the fork extends the air can expand again. Effectively a gas spring. That's why oil level in your forks is important, and why you can change their spring properties by adding and removing oil.
Thankyou Kosta,I appreciate you clearing that up for me and hopefully for many other motorbike riders.👍✨💫
SV 650 Gen 1, classic damping fork rod Spirited road driving above 24 C, pilot 85 to 90 Kg. Stock springs: Motul 15W, a bit too thin for rebound. WP spring: Motul 20W good rebound (need a bit of tuning for the oil level/air gap to prevent harshness on compression).
Thank you for sharing your R&D on the work done so far. A tip of the hat to you!
Thanks, I will try some maxima 20 as I live in a hot climate
2009 Victory Vision. Very heavy bike. Swapped out fork oil for Redline 10wt. Quantity to spec. Very stable behavior and just fine. So far so good, FWIW.
Thank you for posting Karl. It is worth a lot to fellow Victory owners! I appreciate you paying it forward!
I can't read the owner's manual because the forks on my 1967 Kawasaki are actually from an Unknown 80cc MX bike, probably early 80s. The forks have no brand markings and were pulled out of a heap of "old cycle parts" in the 90s. So we have to fall back on first principles with these. They work pretty well on ATF+4, (which I'm told is roughly equivalent to like a 7w fork oil?) but sure do leak a lot with it. Lol
Thanks! This added my knowledge with oils.
Glad that was good content for you to leverage!
Thanks Dave, that was really helpful, I now know what I'm going to try next time I change the fork oil.
I know what type of oil i need, but you got my attention with that funny pun in the title
Thought I was with ya but you said two things that appeared to conflict, and I got confused. First, faster pace riders (weekend twisty road enthusiast vs commuter) might need a lower weight oil, and second that a rider on an MT07 who rides hard on the weekends may prefer the 20w over the 15. I have an MT07 as my first bike, and I've been progressing quickly in my riding, and I've begun thinking about simple/cost effective modifications I can make to suit me better and learn more about motorcycling in general. The suspension is a gripe I hear of continually but, being that it's all I've known, I don't know WHAT I don't know, and I've been wanting to try changing to a different fork oil to see what it does to the handling and whether it's an improvement for me or not. I like to ride briskly (Top of third gear into fourth ~60-80mph in every straight possible between the curves) and brake moderately hard, not at track pace of course - but about as hard as is feasibly safe on public back roads. I weigh 190 pounds and live in an area with a riding season temperature range between about 40 and 95 degrees Fahrenheit. I'm not sure what the best choice could be.
Thank you for your comment. For cartridge forks, sometimes thinner oil is needed for better flow and handling as there are adjusters to use. For damping rod forks thicker oil is needed to create more controlled rebound. With your MT07, 15 or 20w oil will make an enormous difference and start your journey of changes that create positives vs adapting to suspension.
The base oil (base oil is the oil from the refinery without any additives) has a certain VI depending on type of base oil. Mineral base oil has usually a max. VI of 105. And a PAO synthetic (most common synthetic in automotive use) has a VI aprox. 130-160. This VI will not decrease due to shearing. So mineral oils has to be more additivated with VI improver to have a more consistent behavior in chocks. But VI will decrease due to searing over time. Synthetic oil needs non or less VI improver and thus better keep it's viscosity over time. PAO also have a better flow behavior.
Great technical post and thank you for sharing your knowledge!
Ive been thinking about fork oil recently as I need to change it on 4 bikes. I reckon hydraulic fluid would be more than suitable and it is tightly regulated. In its normal application it has to withstand very severe operating conditions, so I doubt it would struggle with bike forks. It also comes in mineral and synthetic types.
Fork oil isn't that expensive to experiment with four bikes.
ATF is what was used before 'fork oil' was invented .
Workshop manual of my Triumph lists the brand and type of ATF to use . Works a treat .
Springs and proper oil at the correct level will transform your bike and greatly improve your riding experience. The difference is amazing
Peter verdone has a chart that's it's weight in gold , and if you know how to chart it onto sheets/excel, it's like sniping a toothpick from a mile away , it's that powerful of a tool.
100% agree.
Peter Verdone is a legend.
Dave you should watch a Project Farm oil test with his flow check of new vs used oils (like a pinewood derby track). Would be interesting to do with various folk oils at hot and cold temps.
Interesting video, having just cleaned/serviced the forks on my Aprilia Pegaso Strada (commuter) and changed to 15W. On the West Coast of Scotland, which was dry (Woo Hoo) the difference was very noticeable in both compression and rebound damping and I could ride a lot harder/faster with improved feedback.
Heading back to Edinburgh, due to rain and average speed camera's the change wasn't so noticeable.
I'll keep notes and try 20W the next time.
Nice work! Thank you for sharing your experience and results.
Thanks for sharing! I have a Strada as well and was planning to do similar changes :)
I've got a 22 CRF 450 and when I got it the forks were solid to move so I got the lightest spring rate from honda and rebuild them to find it's already got the lightest spring in it! I used the correct oil and levels the manufacturer states but it's still a harsh ride I've checked the fork alignment many times and my adjustments are opened right up but it's still crap but I'm about to send the top tubes for a regrind and anodising so I'm trying 5w when I rebuild them this time
I would suggest that you take the chrome and outer tubes and have them put into a lathe and tested for run out to see if the tubes are binding. I would check the bushing as well and look at the chrome tubes for scoring from the bushings.
From Philippines 🇵🇭 😊 Thank you for Sharing 🙂
dave: "the W stands for winter"
also dave: 8:38
:D
thank you for another informative video
Lol, it's so ingrained in our brains these days.
Great video, Dave educating most of us .
Thanks for the super clear explanation 🙌🏼
Brilliant explanation.
useful video:
Question: I know what temperature rear shock oils can and do reach but, not seen figures for 'in use' front fork oil....I'm taking an educated guess in that it's over ambient so that negates worries over regional temperatures.....wouldn't it?
....damper rod front forks typically have a longer stroke than a rear end but, a higher oil capacity and out in the air stream. It can't be that high as I've never seen cooling aids for front forks...? Next time I return from a ride I'll take some temperature reading using my infra red gun.
Luckily I have crude damper rod forks so it's all a finger in the air compromise.
It's a shame fork oil isn't manufactured to strict standards like ATF's....Dexron 3, spot on the spec' as Suzuki/Showa SS8 which is handy if you ride a Wee Strom DL650.....not recommended for the DL1000 which uses cartridges and needs fairy spit.
If you run forks on a dyno, oil temp can reach 100C hence flow rates being posted at 40 & 100C by manufacturers. MX bikes generally
run much higher temps due to velocity/movement.
@@catalystreactionsbw many thanks for the prompt reply Dave, very interesting, take care and stay safe, Richard
The reason for using 'fairy spit' ultra low viscosity fluids is they are more temperature stable than higher viscosities. If there weren't other effects in play, we'd be using water or alcohol for viscosity stability across a temperature range.
Forks have more oil, and most commonly the load divided between 2 forks, and more surface area to providing cooling, so they get less hot than shocks.
Differences in high flow vs high pressure style valves make a big difference in heat and wear... if being aggressively ridden.
Daily commuting with an easy relaxed pace may not even warm forks above cold to the touch.
Extreme MX can have a shock so hot that flash point is being considered...
Hi Dave, you helped me set up my f&r suspension on my 2020 1050XT Suzuki V-Strom via email about a year ago when i got it new. It is really dialed and I love it thanks to your excellent advice. I will be doing my winter service now, including the dump & run on the fork oil. I ride a very spirited pace in the mountains, weigh 164 lbs. w/o gear and carry probably 25 lbs. gear. Based on the CST charts, I am thinking Maxima 7.5W is right. Can I set my oil level/air gap without disassembling and removing springs? My riding temps will vary from 90f-40f. Many thanks as always!!!
Nice Start Dave, love your intro..set the stage, let's be nice and helpful.. cool man cool
Thanks!
Excellent info and explanation, thanks.
I'm old enough to remember when Japanese manufactuers used fish oil in damer rod forks......and you think well used modern fork oil stinks, well you haven't lived.
I remember tearing into an old Hodaka fork and man, smelled worse than rotten cat food and sour milk
M
All my 70s and 80s bikes call for ATF in the forks are fluid, that sticks but not like fish oil.
KYB oil stinks when it's fresh. But when it used.........aghhh
Interesting , i heard you can use auto trans fluid in forks around a 7.5 weight
There are many choicees but please Google an oil viscosity chart first to get your base VI and CsT numbers, then compare with the manufacturer's data if you are considering ATF etc.
It was all very simple when Dave said: RTFM! Then he started with the numbers and i got completely lost. I will stick with RTFM.
Thank you so much !! Great and perfect crystal clear info. Very valuable and a level up on fine tune your forks.
I appreciate you watching and thanks for the kind words! Glad you enjoyed the content.
My 1984 vf750f Honda manual says to use ATF fluid. Is this just simply old technology and now I should use 10w or 15w
ATF is current use for today with your motorcycle , so use it :)
I have a 07 CBR 600RR manual says 10W here in north east.. i commute and weekend drive with friends. I dont wheelies or track . Whats should i used better. Im about to do it this weekend... Brand and W. Thank you
For your CBR you have a colder climate overall. 7 or 7.5w would bve my preference compared to the hot CA Summers where 10w is mandatory.
@@catalystreactionsbw thank you
I got Motul 10W for my Street Triple 765 R 2018 w. Showa SFF BPF. Feels kinda identical to the Showa SS47. Till now...
Oh my Gosh! I can't believe how little I knew about fork oil! Thank you so much for showing me that there is a real measure of viscosity. I just rebuilt the forks on my 2008 GL1800 and added Progressive springs. I'm still trying to decide what fork oil to use. I suspect that I want something a bit heavier than the 10w OE oil made by Showa. If it wasn't such a pain to drain and swap fluid, I would just go in with Maxima Racing 15w and try it out. I have even though about mixing 15w with 10w to get 12.5w.
Would you be kind enough to give me some guidance?
Thank you for your comment and kind words. May I suggest going straight to 15w for your generation of Goldwing. Use the stock volume in the service manual and compare to what you extract prior to deciding how much to put back in. You should notice a small loss post draining compared to the manual amount. Please take that into account.
Dave you the man.. and have u watched that video twist of the wrist 2 video...by Keith code
I know this video is over a year old but I’m just now seeing it. My question is how much does rider weight play into the fork oil choice?
If you change springs due to rider weight, then it comes into play. Oil viscosity relates to spring tension = rebound velocity.
@@catalystreactionsbw thank you for the reply. I only weigh 150lbs so all bikes are oversprung for me.
@@jamesbastiaanse6877 Not all but the majority especially at 600cc and above categories.
9:46 It's not 40cSt and 100cSt. It's the cSt numbers at 40 and 100 degrees Celsius. 1cSt = 1mm^2/s.
Hi Dave. What would recomend for oem k7 gsxr forks? All weather riding, mostly short commutes but I like to have fun out in the lanes too. Your vids are great tools so thanks for your help.
All weathers would generally suggest cooler climate overall with the exception of hot Summer days. My go to would be Maxima 7.5w and stock volume of oil.
@@catalystreactionsbw Cheers Dave. I don't think the oil has been changed once and I have the preload fully soft, despite being about 225-230 in full gear. If I stiffen preload it starts to feel like the front is on the head of a pin and very unstable. Could this be due to the oil being so high in viscosity, being so old? I was planning on changing the forks, with stiffer springs but I just don't have the funds right now.
I was at the track recently and under heavy braking only the front end would judder up and down in small movements. I'm unsure if i am expirenceign cavitation or maybe my discs are so slightly warped. The front wheel doesn't turn freely by hand but i put this down to filthy calipers because my bike is also my daily and the uk roads get rained on a lot so all that shit gets all over my bike every day.
Check the brake pads for angulated wear, then grab the forks by the bottom and see how much free play you have. Could be brakes, bushings or steering head, or a combination.
@@catalystreactionsbw thanks Dave 🙏💫
Thank you for this!
The oem Yamaha 01 fork oil for the mt10 seems to have to same numbers as the motul and maxima 5w , should I stick with that weight when changing do you think , spirited riding two's up on weekends , or shall I go slightly higher in numbers there for needing less preload and more range , I didn't think it would be this hard choosing a fork oil 😁
If you are in a generally cold climate, Y01 oil makes sense. If hotter overall in the 30C range a lot of the time, Maxima/Motul makes more sense
@@catalystreactionsbwmuch appreciated I'll stick to something very close to those viscosity numbers then , just another quick question as I don't fully understsnd the mt10 service manual fork oil level , does it mean 114mm air gap from top of the oil to the top of the fork tube with the spring out if I'm doing seals and if just changing the oil can i just do what you have done on the dump and run when you measure the amount poured out and match that back in again , thanks again for the helpful videos
@@bccapone837 You can do the dump and run but draining will take a while so be patient. Same goes with fresh oil going in. Takes time. Noted on the UK and yes, lighter oil makes sense.
@@catalystreactionsbw much appreciated thank you
Installed Hyperpro springs, with included Hyperpro oil 10W. Standard damping rod forks, freshly rebuilt. Too harsh on sharp bumps, rebound too slow when fully out, almost 20 mm of stiction. Twice tried loosening axle, lower tripple clamps, steering stem nut, bounce the forks to allign everything and torque everything down. Nothing. Decided to dump the Hyperpro oil and put in Motul 10W. Faster rebound, not too fast, down to 10 mm of stiction, and smoother over sharp bumps. Why would they not standardise fork oils? And why so much friction with Hyperpro 10W?
I would respectfully suggest that there is no grease in the grease groove of the oil seal. th-cam.com/video/qK6_7oTF_bI/w-d-xo.html
In regards to standardization of suspension oils - none of us have any idea why but as they say,
it is what it is" and we find our way through it.
@@catalystreactionsbw Thank you for the response, and everything you do to share your knowledge. It means a lot to us DIYers on a low budget. It was greased when installed, I even tried "forcing" some grease by greasing the stanchion and rapidly compressing it, after it didn't help I tried doing the same with silicone spray. Is there any chance that Hyperpro oil is just subpar? I doubt a company would deliberately sabotage themselves with bad oil.
@@catalystreactionsbw That is the exact video _I referred to when trying to fix the problem.
@@KarloZg9000 as usual you covered it perfectly . Ideally one picks a 0 or 2.5 weight oil for the least temp effect. And valve and piston design for that bike using the least weight. I found your reasoning for no mechanical changes to be excellent.
We use belray. Because we are to cheap to buy 55 gallon drum of koni 0 weight which is the only way they sell it. And the only source I know of.
Leadership by example?!!!
Yeah, we were taught the same pay it forward attitude.
Will do, chief!
Hope you and all do yours have a nice 21 summer season.
😉
Great info as always. I have a Moto Guzzi Audace cruiser, 660lb bike + 200lb rider. I'm just about to get my mechanic to upgrade the OEM front and rear suspension to Matris suspension. What weight fork oil do cruisers usually run? I'm looking for sportier more responsive feedback riding at 15°C to 30°C temps.
Matris gives you oil specs and volume for the forks and in general they use 5w or 10w based on the internal piston orifice size.
@@catalystreactionsbw Thanks for your feedback. 🍺🍺🍺
Thank you for your lecture.
One question, is the higher viscosity oil create more bubble during aggressive riding, like track day?
Thank you. Are you referring to air in the oil? Higher viscosity oil by default moves slower so the opportunity for air to be introduced to the oil is limited. Track days are generally easier on suspension as race tracks for the most part are significantly smoother than roads you ride on.
Is it wrong to use 10w40 engine oil in Chinese forks?
Thinking about application and market. Most of these bikes are for far east sale so the small numbers sold here in the west is mhhh to the manufacturer. Accessablity of exotic oil for forks in these regions and the means to purchase, meaning we in the west are blessed to afford such things.
10w40 engine oil in Chinese 125 forks right or wrong?
Most will use ATF for fork fluid, not engine oil.
Dave, Great video, thanks! I have 3 Honda ST1100's (I have issues, LOL) I have Maxima 10W in all 3 bikes.The forks on 2 of them work as they should here in So Cal. My oldest, a 1995 ST's forks feel a little mushy compared to the others yet is very plush on the highway. According to Honda part #s all internals are the same. Cartridge on the right and just a spring on the left.
I can't decide 15W or 20W, what would you recommend? Any help would be greatly appreciated.
Thanks for watching. If mushy and plush go for the 20w and make the oil level slightly lower by 20mm as a starting point.
A lot to take into consideration, fun to tinker with however.
Thank you so much for this work!
Do you have experience with the Tracer 900? What oil would you choose for spirited riding for a 75 KG's rider that typically ride between 10-25 degrees celcius?
I have one in NZ and did all the work on it there in a relatively cold climate. 10w for rebound and 15w for compression. All that work is posted on my website at www.davemosstuning.com and search Tracer GT and "The Long Haul" articles for OEM settings, geometry etc.
Is this numbers for the motul synthetic factory line fork oil? Or the cheaper mineral based fork oils.?
Is maxima fork oil synthetic?
The 2011 gsxr 1000 has the SS-05 for oil stock which is showa 5W not sure if it's synthetic ...would the motul factory line synthetic 5w be a better replacement oil at fork oil service time or should I stick with the suzuki showa SS-05...?
Read the "Forking" manual?
Great video Dave as usual... ... ... ..... .......
If Viscosity Index is important then Amsoil is better with 209 right
Hi Dave,
I live in Las Vegas. I have a 2022 Indian Scout Bobber. I will be installing a Legends AXEO fork suspension but I would like your recommendation of what Maxima fork oil weight to use?
I would recommend the 7.5w oil given the heat of Vegas in the Summer.
Dave, I am changing fork oil on an older yz. It calls for Yamaha 01. Would it be safe to replace it with Maxima 5w?
Still confused.... lol
Bought a 2021 mt07. 215lb rider. No track riding. Just a weekend rider (Toronto, Canada)
Not sure if bike is delivered to the dealer with fork oil, but if it isn't, should I ask the dealer to put a specific W fluid in?
Picking up bike end of month/early July.
Love the videos DMT!
20w for you, stock volume.
Not seeing much examples for a 600cc/1000cc. I have a 2012 kawi zx6r. Definitely ride hard (highways,backroads, mountain, cornering,commuting). As I’m seeing, would a… hmmm… 20w be suitable ? Is this wrong ? I am thinking it terms of what can handle an aggressive riding style. Normal weather/riding conditions range from 50- 95 degree weather and I’m around 190-195lbs athletically built.
Have you set the suspension to your weight and ability and checked fork and shock travel used? That will show if the suspension is too soft or hard and give you the accurate data to guide you to the right changes.
@@catalystreactionsbw I have .. i am actually 170 lb (lost weight) lol . I actually realized the spring rate for the 2012 zx6r are pretty stiff stock (.95kg). All my preload is all the way out and can only achieve a sag of 27mm front. I’m using half of the travel at normal braking and off hard braking I just reach what it seems to be the right buffer before bottoming out. Just recently did fork oil and my tech used 5w.
Looking for a spring rate of .90kg so I may achieve a sag range from 30-40mm up front. Recommend ?
@@junerobinson1220 90 would be a good idea BUT the math must be done in regards to spring length and installed preload as the internal spacer will need to be made shorter. You lack of static sag is a known problem that needs to be resolved.
@@catalystreactionsbw will note that during my inquiries of the right spring 👌. And right, my concern for the lack of static sag is there. Is it okay for the front and rear sag to be different numbers? For now, as my front preload is all out maxing at 27 mm… Can I decrease preload in the rear and get maybe 29-31 mm to get some static sag ? From your videos , I understand a slightly lower front and raised rear helps with turn in?… (although I’m street) My bike is slightly hard to turn in initially but falls into the corner after and follows ( dunlop Q3+) Tire pressure 34 front 36 rear.
@@junerobinson1220 Front can be profoundly different to the rear based on fork and shock travel optimized to your roads and pace. Get 10-12mm static in the rear shock and see how much shock travel is used: th-cam.com/video/KeZT1LCY8CU/w-d-xo.html
I have a 2014 Triumph Tiger ABS, not the XC or any more off-road version. I just purchased the bike a few months ago with about 7800 miles on it. The local service guy says the bike is designed for lighter riders, I'm about 225-230 pounds. He said I should think about changing to higher W oil and maybe different springs. According to Haynes manual the fork is: Showa 43 mm upside-down cartridge forks, non-adjustable. Any suggestions to improve my ride for 85 road - 15 trail, pretty non-aggressive rider.
I would suggest 15w oil and 50ml more than the manual suggests for volume. Thus will be a dump and run project for you! th-cam.com/video/UoIQNcxqaSA/w-d-xo.html
@@catalystreactionsbw Thanks so much for your reply and great videos!!
Motul 10W too hard action & less travel. Motul 7.5W too soft & over travel. Mix both 50/50 equals Motul 8.75W.
Ureka I've done it. Good action & near max travel. May change to Maxima.
7
Hi Dave, if i recall you have a bandit 1250 as well. Would you recommend the RaceTech Gold Valves? I am a 150lb rider that uses the bike across a wide array of roads/styles. I currently have 1.1kg/mm fork springs and Redline 10wt oil. I have tried 1.0kg/mm springs but was unable to achieve proper sag without too much preload and a rough ride. The oil previously was too thick for the heavier springs and produced a harsh ride. Redline 10wt improved ride quality and I plan to try Redline 5wt then mix to a 7.5wt if needed. Handling seems great but I am picky and would like a bit more of a plush ride without costing performance.
Great R&D on oil. A tip of the hat to you. The issue with the forks is the compression pistons in that the valving is very soft hence going to strong springs with lighter oil as the optimal solution. Changing to RT Gold valves will help for sure as they come with a lot more compression valving and use 5w oil for more plush suspension action.
@@catalystreactionsbw I appreciate the feedback! Will you be in the Northern California Bay area this riding season? I plan to hit the tracks after dialing in the suspension on the streets.
@@e46silverbullet62 Yes. Track schedule is here: davemosstuning.com/calendar/
Hey, can someone confirm this theory of mixing viscosity for once and for all? I grew up messing with mountain bike suspension (still do) and I still mess with vintage motorcycle suspension as well as high end stuff (rsv4), so I don't always have the option of adjustable valving, or I do an oil change thinking 10w would be enough only to find its still too thin. From what I remember, to get 12.5w, is it true that you need 3/4 of the volume to be 15w and 1/4 of the volume to be 10w? Or the other way around?
All the mathematics is here: advrider.com/f/threads/mixing-fork-oil-to-get-the-right-viscosity-howto.1454699/
@@catalystreactionsbw Thanks Dave!!
*It's a very close approximation to use a simple proportion equation.* And you should use cst or kinematic viscosity, not 'wt.' Pick the temp range you want (eg cst @ 40C)
In decimal: [desired cst] = Pax[cstA] + (1-Pa)x[cstB] re-arranging that to solve for the P (the proportion):
*Pa= (desiredcst - cstB)/(cstA - cstB)*
multiply that by 100 if you want a percentage
The proportion of B is just the remainder Pb= 1 - Pa, or in percents Pb% = 100% - Pa%
Eg (should be using cst instead of 'wt'):
Pa=(12.5-15)/(10-15)
Pa=0.5
x100, if you prefer = 50%
And since A is 50% B = 100%-50% so coincidentally B= 50% as well.
Which makes sense, because the chosen 12.5cst is halfway between 10 and 15, so no surprise you need a half-and-half proportion to reach that.
If you really care, you will do this and see what the combined effect is at other temperatures too, so you see what your new oil mix line will look like.
*Unless you are an engineer designing something critically sensitive, you should never need to go deeper than simple proportions within the same oil series for determining your mixtures.*
Note: *if your desiredcst is outside the range capable with your mixes, instead of a decimal number, you will get a number greater than one or a negative number, which are non-sensical as a proportion of a whole.*
e.g. 45cst: In reality, what does it mean to add -6 of A? And B being added at 7x the total mix volume? Are we distilling -600%A out of 700% B to end up with 100%? Non-sense for our purposes.
Tiny note, maybe ignore this because you don't need to know it: the mix may not wear evenly with time, so expect a manufacturer created oil to have the most long term stability, but this effect is still likely to be small/insignificant if you've chosen use-stable oils.
Those oingo boingos need lubricant to operate smoothly and the oil serves as resistance through the valves to slow down shock action.
With out oil you are riding an expensive pogo stick. Too much and too thick it’s a lumber wagon with solid axles.
Done correctly it’s smooth sailing with superb control.
Is fork oil just hydraulic fluid, except for the bigger price?
Looking at cSt numbers, 10W seems to correspond ISO VG 32 hydraulic oil, 15W ISO VG 46 oil and 20W ISO VG 68 oil
@@kariholma3850 They should have different additives as they both have different purposes. That being said, I am sure some fork oils are just branded hydraulic oils. I would like to hear details from people i the know.
Personally I use hydraulic oil in my bike's forks. They work well for me. I am not racing though.
The advantages of hydraulic oils are that the data is easy to find and there is a lot less hype and marketing involved so they are cheap enough to be able to optimise your fork's behaviour through trial and error, reaching your preferred viscosity even if that means mixing two standard viscosities:-)
Have on RM 03 125 still not sure what to use any advise would be appreciated
Seriously, the manufacturers & fork oil companies do not provide guidelines as to which oil to use bc it's all relative, like Dave said, to how you're gonna use the bike. I had prior ordered Pro Honda/Showa SS-8 assuming it is most reliable for my CBR600RR.
Nice Vid as always! Thanks! I learn a lot from it! but what Fork oil do you think should I put to my Duke 200 Stock Forks? I use the bike for daily and sundays at twisties, aggresive riding also . I live in the Philippines which is have a mixed weather and temperature around 20C - 35C.
I also have the way to buy Maxima Fork oils.
@@kaiserdgreat I have not seen one in person. Depends on the odometer reading. If the forks are the same as the 390 base model, 15w oil works if you are over 70kgs, 10w if less than that. Maxima is great oil.
@@catalystreactionsbw thank you so much Dave!
FML! why does Ohlins FSK104 cartridge kit tell you to use 40w? Ohlins Oil product reference #20. Wow, this can't be right can it?
This is so damn helpful! The details and how you explained it helped me understand whcih oil grade to use. I have studied this in college, over 2 decades ago and totally forgot it hahaha
Was trying to figure out what WT to use on my MTB fork and now I know. Thank you so much!
Thank you for sharing Dave, in my service book mention 20W for fork oil. I live in mix climate.. Lowest is 15 degree celcius and maximum is around 38 to 39 degree celcius.Is it still ok I use 20w? My small bike is Kawasaki Kaze / modenas kriss
Yes 20w with those temperatures (high/ow) is fine.
Thanks Dave! Very informative.
I'm a layperson, but in layman's terms I've heard that independent of cSt, a higher Viscosity Index oil potentially has greater stiction and isn't as slippery. A super high VI oil may be needed for a shock that can get quite hot, but for a fork, too high of a VI may be detrimental. Is that a linear relationship? Is a higher VI oil always 'stickier' than a lower VI oil, or is it not that simple? Can anyone elaborate?
That is correct and well stated. There is no linear relationship de to various engineering solutions created in each fork from different manufacturers. In the case of Ninja 400 forks with no adjustments, VI ensures that rebound is correct for a given period of time, then it must be replaced when rebound is too fast from broken down oil. With cartridges, most are engineered today for 2.5 or 5w, but internal engineering with valving allows for some flexibility with VI based on regional temps eg Death Valley to Vancouver BC. Hope this helps.
@@catalystreactionsbw Thanks for taking the time to reply. When I got started down this rabbit hole of understanding suspension oils better, I presumed you wanted the highest VI you could get your hands on regardless of application. I guess I know better now. This is all interesting stuff. In a 2019 WR250F (cartridge forks) I'm about to switch from 15.6 cSt OEM fork oil to 18.9. I'm a 240 lb rider. Do you think I'll feel a difference beyond what I can adjust with damping clicks? OK to go thicker?
@@carpetbombing4233 go to 22-24cSt for the WR forks :)
Hi whant to no can i put a stronger rear shock on my xr honda ct 190 this one is to soft and can i put on my front fork tronger oil 20w my weight is 85 kg on the bike i use my bike on the farm
www.tapatalk.com/groups/hondatrailcts/rear-shock-upgrade-for-ct90-t7968-s10.html
what u recomend for speed four triumph??.. i ride it in hotter climate, from 17 Celsius to 35 Celsius... i dont comute with it often.. i ride it more on weekends on highway and mountain roads..tnx
The Speed4 stock forks respond really well to 15w oil with that climate.
@@catalystreactionsbw ok..is motul 15w ok or should i try finding maxima 15w?
@@chevchelios7342 either of those two if available or if not Motorex
@@catalystreactionsbw we have motul and motorex were i live.. i think that every motul product is overprized in my country...i use motorex oil in my bikes, so ill try the fork oil than... tnx a lot man.. ur advise meens a lot.. ur the best
Hi Dave, shop put 10w motul on my rsv4 ohlins forks, I’m around 70kg with gear. Is that ok? Thanks btw I’m in the philippines and it’s always hot.
yes - check the volume or oil height they used for verification. Oil height should be 150mm
@@catalystreactionsbw thanks Dave. Will ask them. I would have wanted 5w or 7.5w but they put 10w on it. Hopefully it won't be too stiff.
Hey Moto jack whats about ur riding experience with 10w after 9month
@@OppoAs-zh1bd not much difference from the stock actually, though now I'm pushing a bit harder and have adjusted the suspension settings properly to my weight.
@@motorjack141 my weight 75 what type of oil and setting recomed for me..... Share with ur experience
does fork oil go bad, unused of course? in other words: how long is the shelf life, stored in a cool dry environment?
If the container is sealed, I would use it 3 years later.
@@catalystreactionsbw thank you for the quick reply. looks like i have to make a trip to the motorcycle store.
Good day sir...how to tune an airshock suspension
And how much oil i put in?
If i understand you correctly, you are talking about air pressure from 90psi to 160psi as an example with a Supermoto air fork. In dialing the air pressure, I always start at the minimum value to see how much movement and how fast the movement is on initial braking and bump compliance. I will also use fork travel used as an additional data point. I will then change to maximum pressure to check harshness, then at 50%. Once you understand the pressure zone that works, then you can explore smaller changes.
@@dominicjohnbalucan2610 As per oil, whatever the manufacturer recommends by w rating and volume.
Hello Dave . im not sure is rider sag ,static sag plus the sag when i sit on the bike or just the amount it sags under my weight ?. thanks Evan
Hi Evan. Static is the bike under its own weight. Rider sag is rider on the bike. Both are added together to create total sag.
Hello Dave. I have a Suzuki VZ800 year 1998. I live in Portugal (minimum temperature 12ºC and maximum temperatures sometimes reach 40ºC). What is the best fork oil to use? 15w ? Thanks
Hi Ricardo. Thank you for your question. 15 or 290w based on your weight and duration of rides (heavier weight if you ride for 1-3 hours at a time at speed vs short urban rides).
My shop manual says SAE 10W20. Ever hear of that?
Yes. Several service manuals spec this oil. Only Repsol make it now so everyone uses 15w.
Thank you Dave, you are master!!
What about 30w in something like a Ninja 650, mostly commute, in average 90F temps? Your missing any 30w numbers, but I guess I should learn to work my own butt ( look it up).
I do have Maxima 30w in my 1986 Yamaha SRX600, plus Progressive fork springs and 10mm longer spacer.
20w is generally the go to oil for that type of fork given the damping orifice size.
What are your thoughts on mineral fork oil... Does it do any damage on a heavy cruiser... I ordered 20w online and didn't realise until I put it in my forks that it's a mineral oil
Mineral oil will not damage your fork internals. There are rubber o-rings and teflon bands inside the cartridge if you have that system. If you have a damper rod, that is simply metal. All good!
@@catalystreactionsbw ... Thanks buddy
do forks actualy get to 100c? 212f? that sounds incredibly high to me. i mean with all the airflow and its not running around a engine.
The metal of the fork does not, but the oil temperature does especially on rough roads due to the velocity of movement that it constantly goes through. Simple friction and pressure.
@@catalystreactionsbw so does the oil in a engine going through pumps, squeezing through bearings, all wrapped up in ferings and it barely gets that hot unless there's a lot of traffic and idleing.
@@nick4506 Great question. The engine has the added heat of combustion along with friction and flow via the pump. Fork and shock dyno's can record oil temps and that is where the data is drawn from.
@@catalystreactionsbw huh interesting. how effective can that static pogo test be, looking for bounces one, if all oil becomes thinner then cool 5w when riding?
difference between the lightest and heaviest at 100c is less than the difference between cool maxima and motul 15w.
Why isn't there multi viscosity fork oil?
Allegedly MotoRace has mutli- viscosity fork oil. Then Motorex makes 5w/10, 10w/20 and 10w/30.
Hi Dave, so i am an 75 kg / 165 lbs rider, riding relatively hard in summer weekends, road bike never been on track, temps 25 to 35 *Celsius, stock suspension on my GSXR 600 k7 (2007) what fork oil do You reccomend?
Motul 7.5w green label.
@@catalystreactionsbw sorry, You mean motul 7.5w with orange-ish label? "road and off road, light-medium, factory line" thats the only one i can find on google...
@@stopii7836 My apologies - typing too fast: maximausa.com/series-290-fork-oil.html?locale=en
@@catalystreactionsbw hey Dave, i got another problem, i cant get maxima oil in Croatia.... can you please please please send me a motul oil link..... i am not sure what motul oil should i use because there is many motul forkoil "factory line, expert, etc.." thank you so much!...
@@stopii7836 Same Motul 7.5w